This invention relates to a printhead for a printing engine, such as a xerographic printing engine, having printing elements arranged in a plurality of arrays and, more particularly, to a printhead with separately energizable parallel arrays of light emitting elements positioned for illumination of a common region of image space.
Xerographic print engines are constructed, typically, with a drum of photosensitive material providing a photoreceptor surface for receipt of a latent image, the drum being operated in conjunction with a developer that converts the latent image to a printable image by use of electrostatic charges for securing toner particles to the photoreceptor surface at the latent image. The latent image is produced by a printhead having sources of light, such as a single line of light-emitting diodes (LEDs) serving as points of an object to be imaged, and an elongated optical focussing element which focuses the line of LEDs upon the photoreceptor surface to produce the latent image.
Due to the construction of printheads with a single line of LEDs, a faulty diode introduces a noticeable pattern in the printed image outputted by the print engine, which pattern manifests itself as a streak or line which is disturbing to a person viewing the printed image. Furthermore, it is recognized that inputted data to the engine, from which data the latent image is created, may be for a relatively low or a relatively high resolution image, yet the engine is capable of printing only at the higher value of resolution.